I don't know about legal punishment, but I think Abby (and others) will be angry with Chad for both beating up Nick (while getting his big brother to help him hush it up) and for waiting until the wedding to make his big, explosive and disruptive announcement. After all, he had plenty of chances to do the right thing long before the wedding, but he waited to get maximum effect for maximum revenge. I doubt that Abby will find that particularly attractive.

Except the big announcement at the wedding seems more likely to be that Nick is not the father of Gabi's baby and he has only just got confirmation of that.

Yes, a few days ago. He still had plent of time rather than quietly sitting through preparations and almost the entire ceremony before disrupting everything. Of course, that wouldn't be as soapy. But still, the guy could have confronted Gabi any time after he overheard her talking with Cameron.

My timelines could be out due to the lack of PBP's but I thought it was the Tuesday 8th of January show where Chad found out via overhearing Cameron that Nick wasn't Gabi's baby dadda.